Metallurgical furnaces are used to process feed material to separate metals and other materials in the feed materials to matte and slag. Various factors, including the rate at which feed material is introduced into a furnace, the rate at which matte and slag materials are drawn from the furnace, the operation of electrodes and control systems for melting equipment may be varied to control the process of converting feed material into matte and slag. It can be desirable to monitor amount of feed material in the metallurgical furnace to control some of these factors and other factors in the operation of a metallurgical furnace.